The correct answer is alcohol. It is the common component in beer, wine and any liquor. Usually, alcohol is produced by fermentation of organic products containing glucose to produce alcohol, specifically ethanol, as the important product and the by-products water and carbon dioxide.
-<u><em>Oxygen</em></u>
According to Google these are the percentages of the <em>Earths Atmosphere</em>
<em>1</em> 78% - Nitrogen
<u>2</u> 21% - Oxygen
<em>3</em> 0.9% - Argon
<em>4 </em>0.3 - Carbon Dioxide with very small percentage of other elements.
The answer should be...99.318!